TextNow - TextNow is a mobile virtual network operator (MVNO) that provides a free phone service to users by using other cellular networks coverage.
RingCentral - RingCentral is the leading provider of cloud-based communications and collaboration solutions for small business and enterprise companies
Google Voice - Google Voice gives you one number for all your phones, voicemail organized in an email format, free...
Dialpad - Switch is a cloud-based phone system built for Google Apps users.
Burner - Disposable phone numbers -- now with MMS photo support
Aircall - Aircall is a call center software of a new generation designed for fast growing companies. Setup instantly and integrates to your CRMs